Animal feed supplement and process of manufacture



E. H. wlGHT ETAL. 2,234,511

ANIMAL FEED SUPPLEMENT AND PROCESS OF MANUFACTURE March 11, 1941.

Filed- March 5,. 1958 Patented Mar. 1l, 1941 UNITED 'STATES ANIMAL FEED SUPPLEMENT AND PROCESS F MANUFACTURE Edward H. Wight. Baltimore, and David L. Anderson, Towson, lMd., assignors to The Davison Chemical Corporation, Baltimore, Md.

Application March 5, 1938, Serial No. 194,198

8 Claims. (Cl. 99-2) Our invention relates to the manufacture of a mineral supplement for animal feed.

An object of this invention is -to produce a calcium and phosphorus containing material suitable for animal feed purposes, by means of a simple process employing a simple inexpensive apparatus of high capacity.

Another object of this invention is to practically eliminate the iluorine from superphospharte to the extent that the fluorine content is greatly reduced over -that present in the original superphosphate.

Yet another object of the i-nvention is to pro vide a process which can be used either with a non-granular superphosphate or preferably with a granular superphosphate as the raw starting material. Still another object of the invention is to prevent during the process the formation of metaphosphates and .to furnish a nal product in which the calcium and phosphates are highly soluble in a water solution of 0.4% HC1.

Our process can be used with ordinary den superphosphate or with the granular superphosphate of commerce. The granular superphosphate may be made by one of several processes,

but the product itself is one in which there are nodular, globoid granules, each granule having indurated and encrusted surfaces. the granules having a crushing strength several times that of fully cured den superphosphate.

The use of the granular superphosphate presents some advantages over the ordinary den superphosphate in that more even heatingvcan be obtained, a more even contact of the moving gases with the surfaces` presented by the granules, and the practical elimination of dust losses. This last item is of considerable importance, and we have found that a process employing Ithe granular superphosphate is highly economical and gives an excellent uniform nal product.

, The material is fed into a rotary kiln whose axis is inclined to the horizontal so that while the material is tumbled in the rotary kiln it will pass from the high feed end towards the low discharge end. v

A burner is located at the lower end of the kiln and hot gases pass up through the kiln towards the high end where they are subjected to the action of an exhaust fan which tends .to suck them vfrom the kiln. During their discharge through the kiln the gasesgive up their heat to the tumbled raw material and calcine this material to a point at which the. fiuorine is practically eliminated. v

'I'he movement of the gases across the material being treated is highly desirable as otherwise a-considerable portion of the total P205 changes to insoluble compounds. In the kiln ,burner V35.

the temperature in general ranges between 600 and 800 C.

The single figure of the drawing shows an apparatus for carrying out our invention, the drawing being largely in longitudinal section.

Referring to the drawing, we have shown a hopper I to which is fed superphosphate. by means of a clam shell bucket or other suitable means. The hopper I is shown partially loaded with superphosphate, as indicated at 2. In the bottom of the hopper I'lies a screw conveyor 3, which is adapted to discharge through an outlet 4 in a chute 5. The chute 5 is closed by means of a hinged door 6.

The feed screw 3 is adapted to` be driven by means of a motor 1 which, through a reduction gearing 8, drives a variable speed transmission 9. At I0 in the chute 5 is shown superphosphate which passes down the chute and is discharged through a discharge end II of the chute 5 into a rotary calciner indicated generally by the numeral I2. The rotary calciner has its axis at a slant to lthe horizontal, having a high end I3 into which the superphosphate to be calcined is delivered, and a lower end Il from which the calcined superphosphate is discharged. The superphosphate passing through the rotary calcincer I2 is indicated by the numeral I5. l

The rotary calciner I2 is provided with a refractory lining I6. One end of the rotary caleiner 12 is restricted, as indicated at I1, and the chute 5 delivers the superphosphate to be calcined through a restricted opening I8 formed at the upper end of the calciner.

Adapted to nt around the upper end of the calciner I2 is an exhaust breeching I9 which, at its upper end is in communication with an exhaust pipe 20 that is connected to an exhaust fan 22. The exhaust fan 22 delivers all exhaust gases throughastack 23. f

In order to rotate the calciner I2, we. have shown rings 24 adapted to travel in rollers 25 l `mounted on supports 26. Motive power to move the calciner`i2 andgive it the desired rotary motion is furnished through a ring gear 21 driven by/a pinion 28 which is mounted on a shaft 29 of a motor 30. There may be reduction gearing between the motor 30 and the pinion 28 if desired. A refractory lined breeching 3i is shown at the lower end Il of the rotary .calciner I2. This-refractory lined breeching is provided with 4a peek hole 32 through which the contents of the fcalciner may be viewed, and an aperture 33 into-which sticks a nozzle 34 of a gas or oil Alt l36 is shown the flame of the burner. The temperature of the material inl the calciner is maintained somewhere between 600 to 800 C. Secondary air is inducted vinto the calciner through the aperture 33 andvthrough a discharge opening 31 formed at the lower end of the refractory breeching Il. Air passes into the opening 31 through apertures Il formed in a support Il which carries a screw conveyor 0. The air which passes in through Athe aperture 33 and through apertures I8 and 31 may be in excess of .that required for complete combustion of the fuel, but the moving gases .tend to reduce the fluorine con-tent of the superphosphate being treated. y

'I'he feed screw 40 is adapted to rotate in the bottom of a water-jacketed trough Il. The caleined superphosphate I2 is partially cooled by the passage of the air through the apertures Il and 31. From the water-iacketed trough 4I the finished material is discharged to storage.

Typical examples of analyses before and after calcination are as follows:

Before After Total P205 percent..- 22.0 27.2 Fluorine do 1.47 0.09

It will be noted that the iluorine is substantially completely eliminated (about 95% removal) and the final product preferably contains not more than .1% fluorine. 'I'he calcining temperature is from 600 to 800 C. and no fusion whatever takes place. The increase of P205 percentage during the calcination is due to the elimination of moisture and hydrate water.

It is pointed out that granular superphosphate is particularly suitable `for this operation, because of the uniformity of particle size and resultant uniform heating. In addition to this,

. bility in a water solution of 0.4% HCl. The reason for this is that this is the acid and approximate strength of the acidity of the digestive juices. The analytical method involves digesting one gram sample in 100 c c. at 65 C. for one hour.

By means of this method as well-as by feeding experiments our deiiuorinated phosphateA shows practically complete availability, the insoluble P205 after calcination being only about 0.4%

out of a total of 27.2%; or 1.47% of the total P205. Another way of stating this is to say that 98.53% of the total P205is soluble. In other words, from 95% to 98.53% of the total P205 is soluble.

It is apparently important that the calcination of the superphosphate is performed under conditions where the material is subjected to a moving current of gas.

'I'he simplest means of accomplishing this is of course the use of direct contact with combustion gases as indicated in the accompanying drawing. Other means of subjecting the material to a current of moving gases can be employed.

If the superphosphate is calcined in the absence of gas currents as for instance in an electric oven, as much as one-fourth of the total P205 changes to insoluble compounds, possibly meta-phosphates, that do not show upY as P205 by the ofllcial analytical method. Moreover, the solubility of the calcined material in 0.4% HCl is unsatisfactory, in fact as much as one-half of the P205 will be insoluble.

We claim:

l. A process for treating superphosphate to render it suitable for animal feed comprising calcining the superphosphate in the presence of heated gas currents between 600 to 800 C. to reduce the fluorine content to not more than .10 percent.

2. In a process for producing animal feed from superphosphates. calcining the superphosphate between temperatures of 600 to 800 C. to remove iiuorine and to increase the availability for animal feed of the calcium and phosphorus contents.

3. A process of treating superphosphate comprising caleining the superphosphate' between temperatures of 600 to 800 C. in the presence of moving currents of heated gas while agitating the superphosphate -to give it a tumbling motion while causing it to move progressively in a given direction with counter-current flow of heated gases to produce an animal feed supplement of low fluorine content.

4. In a process for rendering available for animal food the calcium and phosphorus contents of superphosphate, the step of calcining the superphosphate at temperatures of 600 to 800 C. in a zone of agitation wherein thesuperphosphate is caused to tumble and have a progressive motion in said zone, while subjecting the .superphosphate in its passage through the zone to a counter-current flow of heated gases, whereby the fluorine content is reduced to not more than .1 percent and the P205 content is rendered soluble in .4 percent HC1 to the extent of approximately 98 percent of such P205 content.

5. A process of producing a cattle feed supplement comprising subjecting granular superphosphate consisting of nodules of encrusted and indurated globoid particles to a calcining step at temperatures between 600 to 800 C. where the particles are subjected to a moving current of heated gases.

6. In a process for producing animal feed supplement from granular superphosphate, calcining the granular superphosphate between temperatures of 600 to 800 C. to remove iluorine and to increase the availability for animal feed of the calcium and phosphorus contents.

7. A process for producing animal feed supplement from granular superphosphate comprising calcining the granular superphosphate between temperatures of 600 to 800 C. in a zone of agitation wherein the superphosphate is tumbled and given a progressive motion in said zone and subjecting the material in its passage through the zone to a counter-current ow of heated gases whereby the tluorine content is greatly reduced and approximately 98 percent of the P205 content is rendered soluble in .4 percent HC1.

8. In a process for rendering available for animal food the calcium and phosphorus contents of granular superphosphate. the step of calcining the superphosphate at temperatures of 600 to 800 C. in a zone of agitation wherein the superphosphate is caused Vto tumble and to move progressively in said zone, while subjecting the superphosphate in its passage through the zone to a counter-current flow of heated gases. whereby the iiuorine content is reduced .to not more than .1 percent and the P205 content is rendered soluble in .4 percent HCl to the extent of approximately 98 percent of such P205 content.

H. VVIGHT. DAVID L. ANDERSON. 

